3.1.5.1 Structure of DNA and RNA

Question 1

What are the types of nucleic acid?

Answer 1

DNA (deoxyribonucleic acid)
RNA (ribonucleic acid)

Question 2

What are nucleotides made of?

Answer 2

A pentose sugar (has 5 carbon atoms)
A phosphate group
A nitrogen-containing organic base (includes Cytosine, Thymine, Uracil, Adenine and Guanine)
These parts are joined by a condensation reaction

Question 3

What is a single nucleotide called?

Answer 3

A mononucleotide

Question 4

How do you join two nucleotides together?

Answer 4

A condensation reaction between a deoxyribase sugar and a phosphate group
For each mole of dinucleotide formed, one mole of water is formed
Called a dinucleotide
Joined by a phosphodiester bond

Question 5

What is a chain of nucleotides called?

Answer 5

A polynucleotide

Question 6

What are the parts of DNA/RNA called?

Answer 6

Phosphate
Pentose sugar
Adenine
Guanine
Cytosine
Thymine
Uracil

Question 7

What is RNA?
What are its bases?

Answer 7

Polymer, single chain, relatively short, polynucleotide chain, pentose sugar is ribose, organic bases are adenine, guanine, cytosine and uracil

Question 8

What are the types of RNA?

Answer 8

tRNA: Transfers information from DNA to the ribosomes
mRNA: Makes up ribosomes alongside protein
Involved in protein synthesis

Question 9

What is DNA?
What are its bases?

Answer 9

Pentose sugar is deoxyribose, organic bases are A, T, G and C

Question 10

Which bases are complimentary for DNA/RNA?

Answer 10

Adenine pairs with thymine
Guanine pairs with cytosine

Question 11

What is the structure of DNA?

Answer 11

The two polynucleotide chains wind around eachother to form a double helix which forms the structural backbone
Pentose sugars are anti-parallel (in the opposite direction)

Question 12

What carbons in deoxyribonucleic acid join with what?

Answer 12

Carbon 5 joins to a phosphate above it
Carbon 3 joins to a phosphate below it

Question 13

In DNA, what is the backbone called?

Answer 13

A sugar phosphate backbone

Question 14

What joins bases in DNA/RNA together?

Answer 14

Hydrogen bonds

Question 15

How many hydrogen bonds occur between the bases in DNA?

Answer 15

A and T: two, represnted by ‘=’
C and G: three, represented by three lines, stronger

Question 16

What breaks up a dinucleotide?

Answer 16

A hydrolysis reaction

Question 17

What is the function of DNA?

Answer 17

To give us variation
To give us our physical characteristics- phenotype
DNA gives us proteins then proteins give us our pheontype

Question 18

What makes DNA more robust?

Answer 18

More C to G bonds as there is an extra hydrogen bond which makes it stronger

Question 19

How does DNA’s structure relate to its function?

Answer 19

Very stable structure: rarely mutates
Two strands: allows it to seperate during DNA replication and protein synthesis
Extremely large molecule: carries an immense amount of genetic information
Base pairs within the helical cylinder: genetic information is partly protected from being corrupted by outside chemical/physical forces
Base pairing: DNA can replicate and transfer information as mRNA

Question 20

Why is DNA a polymer?

Answer 20

Because it has repeating monomers

Question 21

How many bases are needed to code for one amino acid?

Answer 21

3

Question 22

Why can a polypeptide have more bases than it needs?

Answer 22

Because some parts of DNA don’t code for proteins
Sometimes it is mutated

Question 23

What is the structure of a nucleotide?

Answer 23

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